• Category
  • Length Range
    30-61 µm
  • Width Range
    7.6-10.3 µm
  • Striae in 10 µm
    15-17 at the valve center, 18-21 at the ends
  • Reported As
    Cymbella incerta (Lange-Bertalot & Mezeltin 1996, plate 61, figs 9-11; plate 95, fig. 15)
    Cymbella incerta (?var.) (Lange-Bertalot and Metzeltin 1996, plate 95, figs 16, 17)



Valves are rhomboid-lanceolate and barely dorsiventral, with both margins tapering to unprotracted apices. The axial area follows nearly the median line of the valve and widens gradually from the apices to the valve center. The axial area is moderately wide and merges smoothly with a small rounded central area. The raphe is lateral and becomes filiform at the proximal and distal ends. The proximal raphe ends are ventrally displaced and terminate with small hooks on the ventral side. Distal raphe ends are shaped like question marks and deflected dorsally. Striae are indistinctly punctate and slightly radiate at the valve center to strongly radiate near the apices. Areolae number 28-34 in 10 µm.


Cymbopleura metzeltinii has been recorded in eight ponds and small lakes in Glacier National Park, Montana. Here pH ranges from 6.73 to 7.78 and specific conductance ranges from 22 to 71 µS/cm. It has also been recorded from Nada Lake, a small lake in Chelan County, Washington (photo below). This species was described from a lake (Mittersee) in the Austrian Tyrol and also reported from a lake in Finland (Julma Ölkky).

Cut  Bank  Pond  Gnp 2
Credit: Loren Bahls
Cut Bank Pond, Glacier National Park, Montana: home of Cymbopleura metzeltinii.
Nada  Lake 4
Credit: Ryan Davis
Nada Lake, Chelan County, Washington: home of Cymbopleura metzeltinii.

Original Description

Valves barely dorsiventral, rhomboid-lanceolate, dorsal and ventral margins tapering continuously to slightly rostrate to apiculate protracted ends. Length 32-67 µm, breadth 8-10.7 µm, maximum length/breadth ratio up to 7. Axial area narrow to moderately wide, almost in the median line of the valve, in larger specimens becoming narrower towards the ends. Central area in the smallest specimens nearly absent, in medium-sized specimens a small, distinctly roundish to elliptical depression on both sides, in post initial cells large (Fig. 115:8). Raphe in the nominate variety distinctly lateral, in var. julma narrowly lateral, narrowing towards the proximal and distal ends, in the middle ventrally displaced. Proximal raphe ends slightly expanded and somewhat ventrally tipped; terminal fissures ?-shaped and dorsally deflected. Striae slightly radiate throughout, indistinctly punctate. Striae in the middle portion (dorsal) 15-16/10 µm, up to 19/10 µm towards the ends, puncta 27-32/10 µm.

  • Author
    Krammer 2003
  • Length Range
    32-67 µm
  • Width
    8.0-10.7 µm
  • Striae in 10µm
    15-16 at the valve center, up to 19 towards the ends

Original Images

Cymbopleura metzeltinii orig illus
Cymbopleura metzeltinii orig descr

Cite This Page

Bahls, L. (2012). Cymbopleura metzeltinii. In Diatoms of North America. Retrieved April 16, 2024, from https://diatoms.org/species/cymbopleura_metzeltinii


The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Cymbopleura metzeltinii from all the stream reaches where it was present. Note that the relative abundance scale is the same on each plot. Explanation of each environmental variable and units are as follows:

ELEVATION = stream reach elevation (meters)
STRAHLER = distribution plot of the Strahler Stream Order
SLOPE = stream reach gradient (degrees)
W1_HALL = an index that is a measure of streamside (riparian) human activity that ranges from 0 - 10, with a value of 0 indicating of minimal disturbance to a value of 10 indicating severe disturbance.
PHSTVL = pH measured in a sealed syringe sample (pH units)
log_COND = log concentration of specific conductivity (µS/cm)
log_PTL = log concentration of total phosphorus (µg/L)
log_NO3 = log concentration of nitrate (µeq/L)
log_DOC = log concentration of dissolved organic carbon (mg/L)
log_SIO2 = log concentration of silicon (mg/L)
log_NA = log concentration of sodium (µeq/L)
log_HCO3 = log concentration of the bicarbonate ion (µeq/L)
EMBED = percent of the stream substrate that is embedded by sand and fine sediment
log_TURBIDITY = log of turbidity, a measure of cloudiness of water, in nephelometric turbidity units (NTU).
DISTOT = an index of total human disturbance in the watershed that ranges from 1 - 100, with a value of 0 indicating of minimal disturbance to a value of 100 indicating severe disturbance.